Which of the following SQL statements will return the year and average salary for all employees
hired within a given year that have a salary greater than $30,000?
A.
SELECT * FROM t1
UNION
SELECT * FROM t2
B.
SELECT * FROM t1
UNION DISTINCT
SELECT * FROM t2
C.
SELECT * FROM t1
INTERSECT
SELECT * FROM t2
D.
SELECT * FROM t1
WHERE (c1,c2)=
(SELECT c1,c2 FROM t2)
With UNION DISTINCT, the result is the set of all rows in either R1 or R2 with the redundant duplicate rows eliminated.
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